Year	1=low to 6=high
2005	3.8
2006	3.9
2007	3.9
2008	3.9
2009	3.9
2010	4
2011	4.1
2012	4.1
2013	4
2014	4
2015	3.9
2016	3.9
2017	3.9
2018	3.9
2019	3.9